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Step 1 - Biochemistry 3
Biochem 3
99
Medical
Graduate
03/20/2014

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Term
Mitochondria metabolism
Definition
Fatty acid oxidation
Acetyl CoA production
TCA cycle
oxidative phosphorylation
Term
Cytoplasm
Definition
Glycolysis
Fatty acid synthesis
HMP shunt
Protein synthesis (RER)
Steroid synthesis (SER)
Cholesterol synthesis
Term
Mitcochondria and Cytoplasm metabolism
Definition
Heme synthesis
Urea cycle
Gluconeogenesis
Term
RLE
Definition
glycolysis- PFK-1
Gluconeogenesis- F-1,6-BP
TCA- Isocitrate dehydrogenase
Glycogen synthesis- glycogen synthase
Glycogenolysis- glycogen phosphorylase
HMP shunt- G6PD
Pyrimidine synth- CPS 2
Purine synth- Glutamine-PRPP-synthetase 2
Urea cycle- CPS 1
FA synthesis- acetyl CoA carboxylase
FA oxidation- Carnitine acyl transferase
Ketogenesis- HMG CoA synthase
Cholesterol synthesis- HMG CoA reductase
Term
Summary of Pathways
Definition
Draw out, pg 98
Term
ATP production
Definition
Aerobic metabolism of glucose produces:
32 ATP- malate aspartate shuttle (heart and liver)
30 ATP- G3P shuttle (muscle)
Anaerobic glycolysis produces only 2 net ATP per glucose
Term
Universal Electron acceptors
Definition
Nicotinamides (NAD from vitamin B3, NADP)
Flavin nucleotides (FAD from vit B2)
NAD is used in catabolic processes to carry reducing eq away
NADPH is used in anabolic processes as a supply of reducing equivalents
NADPH is a product of the HMP shunt; used in anabolic processes, resp burst, p450, glutathione reductase
Term
Hexokinase
Definition
Ubiquitous. High affinity (low km), low capacity.
Feedback inhibited by G6P, unindexed by insulin
"Can run off low amounts of glucose)
Term
Glucokinase
Definition
Within liver and B cells of pancreas
Low affinity, high capacity; induced by insulin
At low glucose levels, hexokinase sequesters it in tissue
At high glucose levels, glucokinase stores it in the liver
Term
Glycolysis Eq require ATP
Definition
Glucose > G6P (hexokinas/glucokinas)
F6P > F-1,6-BP (PFK-1 *RLE)
"Anything with a 6, requires ATP"
Term
Glycolysis Eq that produce ATP
Definition
1,3-BPG <> 3-PG (phosphoglycerate kinase)
PEP > Pyruvate (pyruvate kinase)
Term
Regulation by F-2,6-BP
Definition
Fasting State: Inc glucagon > Inc cAMP > inc PKA > Inc FBPase-2, Dec PFK2, less glycolysis
Fed State: Inc insulin > dec cAMP > Dec PKA > dec FPBase2, Inc PFK2, more glycolysis
Term
Pyruvate Dehydrogenase complex
Definition
Pyruvate + NAD + CoA > ACoA + CO2 + NADH
Needs cofactors:
NAD, FAD, pyrophosphate, CoA, lipoic acid (B1,2,3,5)
Complex is similar to a-KG dehydrogenase complex
*Arsenic inhibits lipoid acid - Vomiting, rice water stools, garlic breath
Term
Pyruvate dehydrogenase complex deficiency
Definition
Causes backup of substrate > lactic acidosis
Most are due to X linked mutation in E1-a (su of PDC)
Neurologic defects, in infancy
Tx: intake of ketogenic nutrients, high fat or lysine/leucine
Term
Alanine Aminotransferase (B6)
Definition
Alalnine carries amino groups to the liver from muscle
Term
Pyruvate carboxylase (biotin)
Definition
oxaloacetate can replenish TCA cycle or be used in gluconeogenesis
Term
Pyruvate dehydrogenase (b1, B2, B3, B5, lipoid acid)
Definition
Transition from glycolysis to the TCA cycle
Term
Lactic acid Dehydrogenase (B3)
Definition
End of anaerobic glycolysis
Major pathway in RBCs, leukocytes, kidney medulla, lens, testes and cornea
Term
TCA (krebs) Cycle
Definition
*Citrate is Krebs starting substrate for making oxaloacetate
OAA > citrate (citrate synthase)
Isocitrate > a-KG (isocitrate dehydrogenase)
aKG > Succinyl CoA (a-KG dehydrogenase)
10 ATP made per 1 acetyl coA
Term
NADH krebs cycle
Definition
Isocitrate > a-KG
a-KG > succinyl CoA
Malate > OAA
Term
GTP Krebs cycle
Definition
Succinyl CoA > Succinate
Term
FADH2 Krebs cycle
Definition
Succinate > Fumarate
Term
ETC and oxidative Phosphorylation
Definition
NADH electrons from glycolysis enter via the malate aspartate or G3P shuttle. FADH2 electrons are transferred to complex 2
NADH = 3 ATP
FADH = 2 ATP
Term
ETC inhibitors
Definition
Directly inhibit electron transport causing dec proton gradient
Rotenone (c1), Cyanide (c4) Antimycin A (c3) and CO (c4)
Term
ATP synthase inhibitors
Definition
Directly inhibit mitochondrial ATP synthase causing inc proton gradient
Oligomycin
Term
Uncoupling agents
Definition
Inc permeability of membrane. ATP synth stops, but ETC continues. Produces heat
2,4-DNP, aspirin, thermogenin (brown fat)
Term
Gluconeogenesis irreversible enzymes
Definition
Pyruvate carboxylase, PEP carboxylase, F-1,6-BP, G6P
Term
Pyruvate carboxylase
Definition
In mitochondria
Pyruvate > carboxylase
Req: biotin, ATP
Act: acetyl CoA
Term
PEP carboxylase
Definition
In cytosol
OAA > PEP
Req: GTP
Term
Fructose-1,6-Bisphosphatase
Definition
In cytosol
F16BP > F6P
Term
G6P
Definition
In ER
G6P > Glucose
Lacking in Mm
Term
Gluconeogenesis
Definition
Occurs primarily in the liver
Also found in the kidney, intestine
Dysfunction causes hypoglycemia
Odd chain FA can enter the TCA cycle as succinyl coA (from propionyl coA) and serve as a glucose source
Even chain FA cannot produce glucose
Term
HMP shunt
Definition
Provides a source of NADPH from G6P
Also yields ribose for nucleotide synthesis and glycolytic intermediates
All occurs in the cytoplasm
*no ATP used or produced
Lactating mammary glands, liver, adrenal cortex, RBCs
Term
HMP shunt rxns
Definition
Oxidative (irreversible)
G6P > Ribulose-5-P and 2NADPH (G6PD *RLE)
Nonoxidative (reversible)
Ribulose-5-P > Ribose-5-P, G3P and F6P
(Phosphopentose isomerase, transketolases - Req B1)
Term
Respiratory Burst
Definition
Activation of membrane bound NADPH oxidase
O2 > O2* > H2O2 > HOCl
NADPH oxidase, SOD, myeloperoxidase
Term
G6PD Deficiency
Definition
NADPH keeps glutatione reduced, which detoxifies free radicals and peroxidases
Dec NADPH leads to hemolytic anemia
Can be caused by fava beans, sulfonamides, primaquine, antituberculosis drugs
Heinz bodies - Oxidized hemoglobin precipitated into RBCs
Bite Cells - results from phagocytic removal of Heinz bodies by splenic macrophages
Term
Essential Fructosuria
Definition
Defect: Fructokinase, autosomal recessive
Benign, asymptomatic
Fructose in blood and urine
Term
Fructose intolerance
Definition
Defect: Aldolase B, autosomal recessive
F-1-P accumulates, causing a dec in available phosphate
Results in inhibition of glycogenolysis and gluconeogenesis
Hypoglycemia, jaundice, cirrhosis and vomiting
Tx: Dec intake of fructose AND sucrose
Term
Galactokinase deficency
Definition
Galactitol accumulates if galactose is present in diet
Mild, autosomal recessive
Galactose in blood and urine, infantile cataracts
Failure to track objects or social smile
Term
Classic galactosemia
Definition
Galactose-1-phosphate uridyltransferase, AR
Damage from accumulation of toxic substances
FTT, jaundice, hepatomegaly, infantile cataracts, MR,
Tx: exclude galactose and lactose from diet
Term
Sorbitol
Definition
Alternative to trapping glucose in cells is to convert it to sorbitol via *Aldolase Reductase
Can also confer sorbitol to fructose via *Sorbitol dehydrogenase
Cataracts, retinopathy, peripheral neuropathy
Term
Lactase deficiency
Definition
Hereditary lactose intolerance due to loss of brush border enzymes
Term
Amino Acids
Definition
Essential- Met, Val, His (gluc) Ile, Phe, Thr, Trp (both) Leu, Lys (Keto)
Acidic- Asp and Glu
Basic- Arg, Lys, His
Term
Urea cycle
Definition
RLE: CPS1 NH4 > Carbamoyl phosphate
Ornithine, Carbamoyl Phosphate, Citrulline, Aspartate, Arginosuccinate, Fumarate, Arginine, Urea
Ornithine transcarbamoylase and RLE are only two in the mitochondria
Term
Alanine and Glutamate transport
Definition
Amino acids > Glutamate > Alanine > Glutamate > Urea
Term
Hyperammonemia
Definition
Acquired or hereditary
Results in excess NH4, which depletes a-KG, leading to inhibition of TCA cycle
Tremor, slurring speech, somnolence, vomiting, cerebral edema, blurring vision
Tx- limit protein, Use benzoate or phenylbutyrate, Lactulose
Term
OTC deficiency
Definition
X linked, body can't eliminate ammonia
Often evident in the first few days of life, may present with late onset
Excess carbamoyl phosphate is converted to orotic acid
Inc orotic acid in blood and urine, Dec BUN, hyperammonemia
Term
Phenylalanine
Definition
Tyrosine (thyroxine) > Dopa > DA > NE > Epi
Needs BH4, B6 and Vit C
Term
Tryptophan
Definition
Niacin > NAD (needs B6)
Serotonin > Melatonin (needs BH4)
Term
Histidine
Definition
Histamine (B6)
Term
Glycine
Definition
Prophyrin > Heme (B6)
Term
Arginine
Definition
Creatine
Urea
NO
Term
Glutamate
Definition
GABA (B6)
Glutathione
Term
Catecholamine synthesis
Definition
Phe > Tyr (Phe hydroylase)
Tyr > Dopa (Try hydroxylase)
Dopa > DA (Dopa decarboxylase)
DA > NE (DA B-hydroxylase)
NE > Epi (Phenylethanolamine N-methyltransferase)
Term
Phenylketonuria
Definition
Dec Phenylalanine hydroxylase deficiency or THB deficiency
Tyrosine becomes essential
MR, growth retardation, seizures, fair skin, eczema, musty odor
Inc tyrosine in diet, dec Phe
Term
Maternal PKU
Definition
Lack of proper dietary therapy during pregnancy
In infnant: microcephaly, MR, growth retardation, congenital heart defects
Term
Alkaptonuria
Definition
Def in homogentisic acid oxidase in the degredative pathways of tyrosine fumarate
Dark connective tissue, brown pigmented sclera, urine turns black after long exposure, arthralgias
Term
Albinism
Definition
Deficiency of either:
Tyrosinase - can't synthesize melanin from tyrosine
Defective tyrosine transporters
Lack of migration of NC cells
Lack of melanin leads to inc risk of skin cancer
Term
Homocystinuria
Definition
Cystathione synthase def - tx: Dec Met, Inc cys, and inc B12 and folate in diet
Dec affinity of cystathione synthase for pyridoxal phosphate - tx inc B6
Homocysteine methyltransferase (req B12) deficiency
MR, osteoporosis, tall stature, kyphosis, lens subluxation, atherosclerosis
Term
Cystinuria
Definition
Hereditary defect of renal tubular amino acid transporter for cysteine, ortnithine, lysine and arginine in the PCT ("COLA")
Precipitation of hexagonal crystals and renal stag horn calculi
Tx: Good hydration and urinary alkalization
Term
MSUD
Definition
a-KG deficiency
Blocked degradation of branched amino acids (Ile, Leu, Val)
CNS defects, MR, death
"I love vermont maple syrup"
Term
Hartnup Dz
Definition
Defective neutral amino acid transporters on renal and interstitial epithelial cells (like cystinuria)
Causes tryptophan excretion in urine and dec absorb in gut
Leads to pellagra (Dermatitis, diarrhea, dementia, death)
Term
Glycogen regulation
Definition
Epi and glucagon stimulate glycogenolysis
Insulin stops glycogenolysis
Term
Glycogen
Definition
Branches have 1,6 bonds; linkages have 1,4 bonds
Sk Mm: G1P > G6P which is rapidly metabolized
Hepatocytes: stored and undergoes glycogenolysis to maintain blood sugar
G6P > G1P > UDP-glucose > chains
Term
Enzymes in Glycogenolysis
Definition
Glycogen synthase (RLE) 1,4 links
Branching enzyme- 1,6 links
Term
Von Gierke's disease (1)
Definition
G6P deficiency
Severe fasting hypoglycemia, Inc glycogen in liver, Inc blood lactate, hepatomegaly
Autosomal recessive
Term
Pompe's disease (2)
Definition
Lysosomal a-1,4-glucosidase
Cardiomegaly, systemic findings > early death
AR "trashes the pump"
Term
Cori's disease (3)
Definition
Debranching enzyme (a-1,6-glucosidase)
Milder form of type 1 with normal blood lactate levels
AR, gluconeogenesis is intact
Term
McArdle's disease (4)
Definition
Sk Mm glycogen phosphorylase
Inc glycogen in muscle, painful Mm cramps, myoglobinuria
Term
Fabry's dz
Definition
a-galactosidase A deficiency
Accumulated: Ceramide trihexidose
Peripheral neuropathy, angiokeratomas, CV/renal dz
*XR
"Fabricate the ceramics gala, eh"
Term
Gaucher's dz
Definition
Glucocerebrosidase deficiency
Accumulated: Glucocererbroside
Most common, Hepatosplenomegaly, aseptic necrosis of femur
*crumpled tissue paper cells
Term
Niemann-Pick dz
Definition
Sphingomyelinase
Acc: Sphingomyelin
neurodegeneration, hepatosplenomegaly, cherry red spot on macula, foam cells
"Pick your brain with your sphinger"
Term
Tay Sachs dz
Definition
Hexosaminidase A
Acc: GM2 ganglioside
Neurodegeneration, cherry red spot on macula, lysosomes with onion skin,
*NO hepatosplenomegaly
"Hex the jew at GM"
Term
Krabbe's dz
Definition
Galactocerebrosidase
Acc: galactocerebrosidase
Peripheral neuropathy, MR, globoid cells
Term
Metachromatic leukodystrophy
Definition
Arylsulfatase
Acc: cerebroside sulfate
Central and peripheral demyelination with ataxia and dementia
Term
Hurler's syndrome
Definition
a-L-iduronidase def
Acc: Heparan and dermatan sulfate
Garoylism, airway obstruction, corneal clouding, hepatosplenomegaly, MR
Term
Hunter's syndrome
Definition
Iduronate sulfatase
Acc: Heparan and dermatan sulfate
Mild hurlers with aggressive behavior
*no corneal clouding
XR
Term
Carnitine Deficiency
Definition
Inability to transport LCFAs into the mitochondria, resulting in toxic accumulation
Weakness, hypotonia, hypoketotic hypoglycemia
Term
Ketone Bodies
Definition
In the liver, FA and AA are metabolize to acetoacetate and B hydroxybutyrate
OAA is depleted for energy in starving state
Term
Fed state
Definition
Glycolysis and aerobic respiration
Insulin stim storage of lipids, proteins and glycogen
Term
Fasting
Definition
Hepatic glygenolysis, gluconeogenesis, adipose release FFA
Term
Starvation day 1-3
Definition
Glucose maintained by hepatic glycogenolysis, adipose release of FFA, hepatic gluconeogensis from tissue lactate and alanine
RBCs cannot use ketones
Term
Starvation after day 3
Definition
Adipose stores, protein degredation
Term
Cholesterol synthesis
Definition
RLE is HMG CoA reductase
Statins block this
Term
Lipid transport, key enzymes
Definition
LCAT - catalyze esterification of cholesterol
CEPT- mediates transfer of cholesterol esters to other lipoprotein particles
Term
Apo E
Definition
Mediates remnant uptake
On every type
Term
Apo A1
Definition
Activates LCAT
On HDL, maybe CM
Term
Apo C2
Definition
LPL cofactor
On CM, VLDL and HDL
Term
Apo B48
Definition
CM secretion
On CM and CM remnant
Term
Apo B100
Definition
Binds LDL receptor
On VLDL, IDL and LDL
Term
Chylomicron
Definition
Delivers dietary TGs to peripheral tissues
Cholesterol to liver in form of remnant
Secreted by intestinal epithelial cells
Term
VLDL
Definition
Hepatic TGs to peripheral tissues
Liver
Term
IDL
Definition
Delivers TGs and cholesterol to liver
Term
LDL
Definition
Delivers hepatic cholesterol to peripheral tissues
Term
HDL
Definition
Mediates reverse cholesterol transport from periphery to liver
Secreted by both liver and intestine
Term
Hyper chylomicronemia (1)
Definition
LPL deficiency or altered Apo C2
Inc CM, TG, cholesterol
pancreatitis, hepatosplenomegaly, eruptive xanthomas
Term
Familia hypercholesterolemia (2)
Definition
Absent LDL R
Inc, LDL, cholesterol
Accelerated atherosclerosis, tendon xanthomas, corneal arcus
Term
Hypertriglyceridemia (4)
Definition
hepatic over production of VLDL
Inc VLDL and TG
Pancreatitis
Term
Abetalipoproteinemia
Definition
AR in MTP gene
Dec B-48 and B100
Dec CM and VLDL synthesis and secretion
Lipid accumulation in enterocytes
FTT, steattorrhea, acantholysis, ataxia, night blindness
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